Reproduction, or copying, systems have been known and utilized for some time. Among the more successful of such systems is that accomplished electrophotographically, and many types of machines and methods for accomplishing the desired end have been proposed and/or utilized.
As would be expected, copying machines, including auxiliary devices used in combination therewith or as a part thereof, have undergone many refinements and, at least in some cases, while such refinements have greatly increased the usefulness of such machines, these refinements have also increased costs as well as presenting problems in assuring complete copying of originals.
Included in the many refinements to copying machines that have heretofore been suggested or have occurred, is the development of auxiliary devices for feeding originals to the copying area of the copying machine, including automatic feeding, and development of collating, or collecting, devices to receive and handle the copy sheets forwarded from the copying area after copying has occurred. Document feeding devices are shown, for example, in U.S. Pat. Nos. 3,552,739; 3,556,511; 3,556,512; 3,556,513; 3,565,420; 3,630,515; and 3,815,896, while copy collecting devices are shown, again by way of example, in U.S. Pat. Nos. 3,460,824 and 3,841,754.
Also included in the many refinements in copying machines that have heretofore been suggested or have occurred is the development in such machines of the capability to make duplex copies (i.e., to copy on both sides of a sheet of copy paper). This is important not only where exact copying is desired of duplex original documents, but it is also important in other respects as, for example, in saving paper costs and/or filling space. Duplex copying is shown, for example, in U.S. Pat. Nos. 3,615,129; 3,645,615; and 3,841,754, with the latter including a feeding mechanism and a sorting, or collecting, device in conjunction therewith.
Duplex copying from simplex originals can normally be accomplished today on many different types of copying machines. The degree of difficulty encountered, as well as the required handling of originals and/or copies, depends, however, at least in part, upon the degree of sophistication of the operator.
In addition, at least some commonly available commercial copying machines can provide automatic generation of duplex copies, but the required components and/or circuitry involved is complicated and results in costs for such units that are higher than might be justified to at least some users.
For duplex copying from either simplex or duplex originals, assurance of complete copying, as desired, for each original, has presented additional problems, even when using automatic machines for generating duplex copies, particularly where jams occur during second side copying. While the copying device could be stopped, the jam cleared, new first side copies generated, the newly generated copies positioned to replace the jammed copies, and the run then continued to make the desired second side copies each time that a jam occurred, this would obviously be not only timewise inefficient, but would also be complicated and possibly inexact, and therefore unacceptable for many uses and/or users.
As an alternative, each jam could, of course, be cleared from the copying machine and the run completed with or without regard for missing copies, but the generated stack of copies would then have to be carefully reviewed for missing copies, if not flagged, the corresponding originals found in the stack of originals and rerun, and then the newly generated copies inserted in the stack of copies and the corresponding originals returned to the stack of originals. Here again, this would be timewise inefficient as well as requiring a considerable amount of document and copy handling.
Apparatus has been suggested for enabling more precise selection of copies that need to be recopied after a jam. See, for example, U.S. Pat. No. 3,588,472 where a jam is detected and an operator is informed of the amount of back-up necessary for completion of copying by counting the number of sheets entering the transport path of the copying device and counting the number of sheets emerging from the transport path followed by comparing these counts with the number of copies desired and providing a count for display utilizing a reversible counter.
Job recovery apparatus and methods heretofore suggested for replacement of jammed copies, do not, however, permit a normal run to be completed before missing copies, due to jams, are made without requiring extensive manual sorting and/or handling of documents and/or copies.